Semiconductor device and memory system

ABSTRACT

A semiconductor device includes a first transistor; a first resistor; a second resistor; a first circuit configured to apply a first voltage to the first transistor. The first voltage is based on a difference between a reference voltage and an output voltage divided by the first and second resistors. A first current through the first circuit in a first mode is less than a second current through the first circuit in a second mode. The semiconductor device includes a capacitor connected to the output terminal; and a second circuit connected to the capacitor that: (a) disconnects the first circuit from the capacitor and apply a second voltage to the capacitor in a first mode, and (b) electrically connects the first circuit to the capacitor in the second mode.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2020-042001, filed on Mar. 11, 2020, theentire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a semiconductor deviceand a memory system.

BACKGROUND

A semiconductor device and a memory system including a series regulatorare known.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a semiconductor device according to a firstembodiment.

FIG. 2 is a block diagram of a memory chip provided in the semiconductordevice according to the first embodiment.

FIG. 3 is a circuit diagram of a memory cell array in the memory chipprovided in the semiconductor device according to the first embodiment.

FIG. 4 is a block diagram of a power supply circuit provided in thesemiconductor device according to the first embodiment.

FIG. 5 is a circuit diagram of an HP mode regulator in the power supplycircuit provided in the semiconductor device according to the firstembodiment.

FIG. 6 is a circuit diagram of an LP mode regulator in the power supplycircuit provided in the semiconductor device according to the firstembodiment.

FIG. 7 is a timing chart illustrating the voltage of each wiring in theHP mode regulator in the power supply circuit provided in thesemiconductor device according to the first embodiment.

FIG. 8 is a circuit diagram of the HP mode regulator in the power supplycircuit provided in the semiconductor device according to a firstexample of a second embodiment.

FIG. 9 is a timing chart illustrating the voltage of each wiring in theHP mode regulator in the power supply circuit provided in thesemiconductor device according to the first example of the secondembodiment.

FIG. 10 is a circuit diagram of the HP mode regulator in the powersupply circuit provided in the semiconductor device according to asecond example of the second embodiment.

FIG. 11 is a timing chart illustrating the voltage of each wiring in theHP mode regulator in the power supply circuit provided in thesemiconductor device according to the second example of the secondembodiment.

FIG. 12 is a circuit diagram of the HP mode regulator in the powersupply circuit provided in the semiconductor device according to a thirdexample of the second embodiment.

FIG. 13 is a circuit diagram of the HP mode regulator in the powersupply circuit provided in the semiconductor device according to afourth example of the second embodiment.

FIG. 14 is a timing chart illustrating the voltage of each wiring in theHP mode regulator in the power supply circuit provided in thesemiconductor device according to the fourth example of the secondembodiment.

FIG. 15 is a circuit diagram of the HP mode regulator in the powersupply circuit provided in the semiconductor device according to a fifthexample of the second embodiment.

FIG. 16 is a timing chart illustrating the voltage and current of eachwiring in the HP mode regulator in the power supply circuit provided inthe semiconductor device according to the fifth example of the secondembodiment.

FIG. 17 is a circuit diagram of the HP mode regulator in the powersupply circuit provided in the semiconductor device according to a sixthexample of the second embodiment.

FIG. 18 is a timing chart illustrating the voltage and current of eachwiring in the HP mode regulator in the power supply circuit provided inthe semiconductor device according to the sixth example of the secondembodiment.

FIG. 19 is a block diagram of the power supply circuit provided in thesemiconductor device according to a third embodiment.

FIG. 20 is a circuit diagram of an HP/LP mode regulator in the powersupply circuit provided in the semiconductor device according to thethird embodiment.

FIG. 21 is a timing chart illustrating the voltage of each wiring in theHP/LP mode regulator in the power supply circuit provided in thesemiconductor device according to the third embodiment.

FIG. 22 is a block diagram of the semiconductor device according to afourth embodiment.

FIG. 23 is a block diagram of an information terminal system includingthe semiconductor device according to a fifth embodiment.

DETAILED DESCRIPTION

Embodiments provide a semiconductor device and a memory system which arecapable of improving a processing capacity thereof.

In general, according to one embodiment, a semiconductor device having aregulator having first and second operation modes. The regulatorincludes: a first transistor including a first end configured to beconnected to a power supply voltage and a second end connected to anoutput terminal; a first resistor having a first end connected to thefirst transistor and the output terminal; a second resistor having afirst end connected to a second end of the first resistor and a secondend connected to a ground voltage; a first circuit configured to apply afirst voltage to a gate of the first transistor, wherein the firstvoltage is determined based on a difference between a reference voltageand an output voltage divided by the first and second resistors, andwherein a first bias current flowing through the first circuit in thefirst operation mode is less than a second bias current flowing throughthe first circuit in the second operation mode; a capacitor including afirst electrode connected to the output terminal; and a second circuitconnected to a second electrode of the capacitor and configured to: (a)electrically disconnect the first circuit from the first capacitor andapply a second voltage to the first capacitor in the first operationmode, and (b) electrically connect the first circuit to the capacitor inthe second operation mode.

Each functional block may not necessarily be distinguished as in thefollowing examples. For example, some functions may be executed byfunctional blocks different from illustrated functional blocks.Furthermore, the illustrated functional block may be divided intofurther detailed functional sub-blocks. The embodiments are not limitedby which any functional blocks are specified.

In the present specification and claims, when one first element isreferred to as being “connected to” another second element, the firstelement is directly or always or selectively connected to the secondelement via an element that is electrically conductive.

1. First Embodiment

A semiconductor device according to a first embodiment will bedescribed. Hereinafter, a memory system will be described as an exampleof the semiconductor device.

1.1 Configuration

1.1.1 Configuration of Memory System

First, an example of a configuration of the memory system will bedescribed with reference to FIG. 1. FIG. 1 is a block diagramillustrating an example of a configuration of the memory system 1.

As illustrated in FIG. 1, the memory system 1 includes a plurality ofnonvolatile memory chips 10 and a memory controller 20, and is connectedto an external host device 2. The nonvolatile memory chips 10 and thememory controller 20 constitute one memory system 1 by, for example, acombination thereof. Examples of such a memory system 1 may include amemory card such as an SD™ card, a Solid State Drive (SSD), an embeddedMultimedia Card (eMMC), and a Universal Flash Storage (UFS).Hereinafter, the respective nonvolatile memory chips 10 will be simplyreferred to as the memory chip 10.

Each of the memory chip 10 and the memory controller 20 includes a powersupply circuit 30. The power supply circuit 30 supplies a power supplyvoltage to each circuit provided in the memory chip 10 or the memorycontroller 20. A case where the power supply circuit 30 of the memorychip 10 and the power supply circuit 30 of the memory controller 20 havethe same circuit configuration will be described below. In addition, thepower supply circuit 30 in the memory chip 10 and the power supplycircuit 30 in the memory controller 20 may have different circuitconfigurations.

The power supply circuit 30 in the memory chip 10 is supplied with avoltage VCCQ_M from the outside (e.g., the host device 2). Further, thepower supply circuit 30 in the memory controller 20 is supplied with avoltage VCCQ_C from the outside (e.g., the host device 2). The voltageVCCQ_M and the voltage VCCQ_C may have the same voltage value ordifferent voltage values.

The memory chip 10 is, for example, a semiconductor chip in which anonvolatile memory such as an NAND flash memory is built. The NAND flashmemory may be, for example, a three-dimensionally stacked NAND flashmemory. An example of the memory chip 10 as a three-dimensionallystacked NAND flash memory will be described below.

The memory controller 20 commands the memory chip 10 to perform a dataread operation, a data write operation, or a data erase operation, forexample, in response to a request (command) from the host device 2. Thememory controller 20 may be, for example, a system on a chip (SoC). Inaddition, each function of the memory controller 20 may be implementedby a dedicated circuit, or may be implemented as a processor executesfirmware. In the present embodiment, a case where a dedicated circuit isprovided in the memory controller 20 will be described.

The memory controller 20 includes a host interface (host I/F) circuit21, a Random Access Memory (RAM) 22, a Central Processing Unit (CPU) 23,a buffer memory 24, a memory interface (memory I/F) circuit 25, and anError Check and Correction (ECC) circuit 26. These circuits areconnected to each other via an internal bus.

The host interface circuit 21 is connected to the host device 2 by ahost bus and takes charge of communication with the host device 2. Forexample, the host interface circuit 21 transfers commands and datareceived from the host device 2 to the CPU 23 and the buffer memory 24,respectively. Further, the host interface circuit 21 transfers, forexample, data in the buffer memory 24 to the host device 2 in responseto a command from the CPU 23.

The RAM 22 is, for example, a semiconductor memory such as a DRAM, andstores, for example, firmware or various management tables for managingthe memory chip 10. Further, the RAM 22 is also used as a work area forthe CPU 23.

The CPU 23 controls an operation of the overall memory controller 20.The CPU 23 controls the host interface circuit 21, the RAM 22, thebuffer memory 24, the memory interface circuit 25, and the ECC circuit26. For example, the CPU 23 issues a write command in response to awrite command received from the host device 2 and transmits the issuedwrite command to the memory interface circuit 25. This operation is thesame for a read command and an erase command. Further, the CPU 23executes various processes for managing the memory space of the memorychip 10 such as wear leveling.

The buffer memory 24 temporarily stores, for example, read data receivedby the memory controller 20 from the memory chip 10 and write datareceived by the memory controller 20 from the host device 2.

The memory interface circuit 25 is connected to the memory chip 10 andtakes charge of communication with the memory chip 10. In the example ofFIG. 1, the memory interface circuit 25 has two channels CH0 and CH1.Then, the plurality of memory chips 10 are connected to the channels CH0and CH1. For example, at the time of a write operation, the memoryinterface circuit 25 transmits written data in the buffer memory 24, anaddress signal, a write command issued by the CPU 23, and variouscontrol signals to the memory chip 10. Further, for example, at the timeof a read operation, the memory interface circuit 25 transmits anaddress signal, a read command issued by the CPU 23, and various controlsignals to the memory chip 10 and transmits read data received from thememory chip 10 to the buffer memory 24.

The ECC circuit 26 executes an Error Checking and Correcting (ECC)processing of data.

1.1.2 Configuration of Memory Chip

Next, an example of the overall configuration of the memory chip 10 willbe described with reference to FIG. 2. FIG. 2 is a block diagramillustrating an example of a configuration of the memory chip 10.

As illustrated in FIG. 2, the memory chip 10 includes a power supplycircuit 30, a memory cell array 11, a row driver 12, a row decoder 13, asense amplifier 14, a voltage generation circuit 15, and a sequencer 16.

The memory cell array 11 includes a plurality of blocks BLK (BLK0, BLK1,BLK2, . . . ). Each of the blocks BLK includes a plurality of (four inthe present embodiment) string units SU (SU0 to SU3). The string unit SUis a set of a plurality of NAND strings NS in which a plurality ofmemory cell transistors are connected in series. In addition, the numberof blocks BLK in the memory cell array 11 and the number of string unitsSU in the block BLK are freely selected.

The row driver 12 supplies a voltage applied from the voltage generationcircuit 15 to the row decoder 13 based on an address signal (e.g., pageaddress signal) received from, for example, the memory controller 20.

The row decoder 13 decodes a row address based on an address signal(e.g., block address signal) received from, for example, the memorycontroller 20. The row decoder 13 selects any of the blocks BLK based onthe decoding result and interconnects the selected block BLK and the rowdriver 12.

The sense amplifier 14 senses data read from any string unit SU of anyblock BLK when reading data. Further, the sense amplifier 14 supplies avoltage depending on write data to the memory cell array 11 when writingdata.

The sequencer 16 controls an operation of the entire memory chip 10.More specifically, the sequencer 16 controls, for example, the voltagegeneration circuit 15, the row driver 12, the row decoder 13, and thesense amplifier 14 at the time of a write operation, a read operation,and an erase operation.

The voltage generation circuit 15 is supplied with a power supplyvoltage supplied from the power supply circuit 30. The voltagegeneration circuit 15 generates a voltage used for a write operation, aread operation, and an erase operation and supplies the voltage to therow driver 12 and the sense amplifier 14, for example, based on thecontrol of the sequencer 16.

1.1.3 Circuit Configuration of Memory Cell Array

Next, a circuit configuration of the memory cell array 11 will bedescribed with reference to FIG. 3. FIG. 3 is a diagram illustrating anexample of a circuit configuration of the memory cell array 11. Theexample of FIG. 3 illustrates the block BLK0, but configurations of theother blocks BLK are also the same.

As illustrated in FIG. 3, the block BLK0 includes, for example, fourstring units SU0 to SU3. Then, each string unit SU includes a pluralityof NAND strings NS. Each of the NAND strings NS includes, for example,eight memory cell transistors MC (MC0 to MC7) and select transistors ST1and ST2. The memory cell transistor MC includes a control gate and acharge storage layer, and stores data in a nonvolatile manner.

In addition, the memory cell transistor MC may be of an MONOS type usingan insulating film for the charge storage layer or of a floating gate(FG) type using a conductive layer for the charge storage layer.Further, the number of memory cell transistors MC in the NAND string NSis not limited to eight, and may be 16, 32, 64, 96, or 128, for example,without being limited thereto. Further, the number of select transistorsST1 and ST2 in the NAND string NS may be one or more.

In the NAND string NS, the respective current paths of the selecttransistor ST2, the memory cell transistors MC0 to MC7, and the selecttransistor ST1 are connected in series in this order. Then, a drain ofthe select transistor ST1 is connected to a corresponding bit line BL.Further, a source of the select transistor ST2 is connected to a sourceline SL.

Control gates of the memory cell transistors MC0 to MC7 of each NANDstring NS in the block BLK are connected to different word lines WL0 toWL7. More specifically, for example, the control gates of the memorycell transistors MC0 in the block BLK0 are commonly connected to theword line WL0. The control gates of the memory cell transistors MC1 inthe block BLK0 are commonly connected to the word line WL1. Arelationship between the other memory cell transistors MC2 to MC7 andthe word lines WL2 to WL7 is the same.

Gates of the select transistors ST1 of the respective NAND string NS inthe string unit SU are connected to select gate lines SGD. Morespecifically, the gates of the select transistors ST1 in the string unitSU0 are commonly connected to a select gate line SGD0. The gates of theselect transistors ST1 (not illustrated) in the string unit SU1 arecommonly connected to a select gate line SGD1. The gates of the selecttransistors ST1 (not illustrated) in the string unit SU2 are commonlyconnected to a select gate line SGD2. The gates of the selecttransistors ST1 (not illustrated) in the string unit SU3 are commonlyconnected to a select gate line SGD3.

Gates of the select transistors ST2 in the block BLK are commonlyconnected to select gate line SGS. In addition, the gates of the selecttransistors ST2 may be connected to different select gate lines SGS foreach string unit SU, like the gates of the select transistors ST1.

Drains of N (N is an integer of 1 or more) select transistors ST1 in thestring unit SU are connected to different bit lines BL (BL0 to BL(N-1)),respectively. That is, the NAND strings NS in the string unit SU areconnected to different bit lines BL, respectively. Further, in eachblock BLK, one NAND string NS in the string unit SU0, one NAND string NSin the string unit SU1, one NAND string NS in the string unit SU2, andone NAND string in the string unit SU3 are commonly connected to the bitline BL.

Sources of the select transistors ST2 in the blocks BLK are commonlyconnected to the source line SL.

That is, the string unit SU is a set of the NAND strings NS that areconnected respectively to different bit lines BL and that are connectedto the same select gate line SGD. Further, the block BLK is a set of thestring units SU that share the word lines WL. Then, the memory cellarray 11 is a set of the blocks BLK that share the bit lines BL.

1.1.4 Configuration of Power Supply Circuit 30

Next, a configuration of the power supply circuit 30 will be describedwith reference to FIG. 4. FIG. 4 is a block diagram illustrating anexample of a configuration of the power supply circuit 30. The powersupply circuit 30 in the memory chip 10 will be described below, but thepower supply circuit 30 in the memory controller 20 is the same.

The power supply circuit 30 of the present embodiment has two operationmodes including a low power operation mode (hereinafter referred to as“LP mode”) and a high power operation mode (hereinafter referred to as“HP mode”). The LP mode is, for example, an operation mode that isselected when the memory chip 10 (or the memory system 1) is in thestandby state to reduce power consumption (current consumption) in thepower supply circuit 30. The HP mode is selected, for example, when thememory chip 10 (or the memory system 1) is in the active state. Forexample, the memory controller 20 sets the power supply circuit 30 ofthe selected memory chip 10 which is selected for performing a writeoperation, for example, to the HP mode and sets the power supply circuitof the non-selected memory chip 10 to the LP mode. That is, theoperation mode of the power supply circuit 30 of the memory chip 10 isswitched according to a switching operation of the memory chip 10.

As illustrated in FIG. 4, the power supply circuit 30 includes areference voltage generation circuit 31, a logical control circuit 32,an HP mode regulator 33, and an LP mode regulator 34.

The reference voltage generation circuit 31 is supplied with, forexample, the voltage VCCQ_M (in case of the memory controller 20, thevoltage VCCQ_C). The reference voltage generation circuit 31 supplies areference voltage VREF_HP to the HP mode regulator 33 and supplies areference voltage VREF_LP to the LP mode regulator 34. The voltageVREF_HP and the voltage VREF_LP may have the same voltage value ordifferent values.

The logical control circuit 32 transmits a switching signal between theHP mode and the LP mode and various control signals to the HP moderegulator 33 and the LP mode regulator 34.

The HP mode regulator 33 is a regulator used in the HP mode. Detailsthereof will be described below. The HP mode regulator 33 outputs avoltage VOUT in the HP mode.

The LP mode regulator 34 is a regulator used in the LP mode. Detailsthereof will be described below. The LP mode regulator 34 outputs avoltage VOUT in the LP mode. The power consumption of the LP moderegulator 34 is less than that of the HP mode regulator 33. Further, theLP mode regulator 34 has a slower response to the variation of anexternal load that supplies an input voltage or the output voltage VOUTthan the HP mode regulator 33.

1.1.5 Configuration of HP Mode Regulator

Next, an example of a configuration of the HP mode regulator 33 will bedescribed with reference to FIG. 5. FIG. 5 is a circuit diagramillustrating an example of a configuration of the HP mode regulator 33.

In addition, in the following description, when a source and a drain ofa transistor are not limited, one of the source or the drain of thetransistor is referred to as “one end of the transistor”, and the otherone of the source and the drain of the transistor is referred to as “theother end of the transistor”.

As illustrated in FIG. 5, the HP mode regulator 33 includes terminals T1and T2, resistance elements (e.g., resistors) RA and RB, capacitorelements (e.g., capacitors) C1 and COUT, a p-channel Metal OxideSemiconductor Field Effect Transistor (MOSFET) (hereinafter alsoreferred to as “PMOS transistor”) Mdrv, a differential amplifier circuit310, and a mode switching circuit 320.

The terminal T1 functions as an input terminal of the differentialamplifier circuit 310. The reference voltage VREF_HP is input to theterminal T1 for constant voltage control by the HP mode regulator 33.

The terminal T2 functions as an output terminal of the HP mode regulator33. The voltage VOUT is output from the terminal T2. The terminal T2 isconnected, for example, to the voltage generation circuit 15 in thememory chip 10. The terminal T2 is connected to a node N17 in the HPmode regulator 33.

The resistance elements RA and RB function as a voltage dividing circuitfor the output voltage VOUT. The resistance element RA has one endconnected to the node N17 and the other end connected to a node N7. Theresistance element RB has one end connected to the node N7 and the otherend connected to a node N2 (hereinafter also referred to as “groundvoltage wiring”) to which a ground voltage VSS is applied. The voltageapplied to the node N7 is VD, the resistance value of the resistanceelement RA is rA, and the resistance value of the resistance element RBis rB. Then, a relationship between the output voltage VOUT and thevoltage VD is VD=VOUT×(rB/(rA+rB)).

The capacitor element COUT functions as an output condenser. Thecapacitor element COUT prevents the fluctuation of the output voltageVOUT due to, for example, the variation of the external load connectedto the terminal T2 or the variation of a voltage VIN. The capacitorelement COUT has one side electrode connected to the node N17 and theother side electrode connected to the node N2.

The capacitor element C1 is provided for phase compensation in the HPmode. The capacitor element C1 has one side electrode connected to anode N15, i.e., the mode switching circuit 320 and the other sideelectrode connected to the node N17. For the capacitor element C1, forexample, an element having a relatively large capacitance is used forphase compensation.

The PMOS transistor Mdrv functions as an output driver of the HP moderegulator 33. In order to keep the output voltage VOUT of the HP moderegulator 33 constant, a gate voltage Vpg of the PMOS transistor Mdrvchanges according to the variation of the output voltage VOUT, so thatthe ON-resistance of the PMOS transistor Mdrv is adjusted. The PMOStransistor Mdrv has one end connected to a node N1 (hereinafter alsoreferred to as “power supply voltage wiring”) to which the voltage VIN(e.g., the voltage VCCQ_M) is applied and the other end connected to thenode N17. A gate of the PMOS transistor Mdrv is connected to thedifferential amplifier circuit 310 via a node N10, and the voltage Vpgis applied to the gate.

The differential amplifier circuit 310 compares the reference voltageVREF_HP with the voltage VD, and outputs the voltage Vpg depending onthe difference. The differential amplifier circuit 310 includes PMOStransistors M3, M4, M7, and M8, and n-channel MOSFETs (hereinafter alsoreferred to as “NMOS transistors”) M1, M2, M5, M6, Mb1, Mb2, Mb3, Mb4,and Ms1.

The PMOS transistor M3 has one end connected to the node N1 and theother end and a gate which are connected to a node N3.

The NMOS transistor M1 has one end connected to the node N3 and theother end connected to a node N5. A gate of the NMOS transistor M1 isconnected to the terminal T1, and the reference voltage VREF_HP isapplied to the gate.

The PMOS transistor M4 has one end connected to the node N1, and theother end and a gate which are connected to a node N4.

The NMOS transistor M2 has one end connected to the node N4 and theother end connected to the node N5. A gate of the NMOS transistor M2 isconnected to the node N7, and the voltage VD is applied to the gate.

The NMOS transistor Mb1 has one end connected to the node N5 and theother end connected to the node N2. A voltage VB1 is applied to a gateof the NMOS transistor Mb1.

The NMOS transistor Mb2 has one end connected to the node N5 and theother end connected to a node N6. The voltage VB1 is applied to a gateof the NMOS transistor Mb2.

The NMOS transistor Ms1 has one end connected to the node N6 and theother end connected to the node N2. A signal Smd is input to a gate ofthe NMOS transistor Ms1.

The voltage VB1 is a bias voltage for generating current IA flowingthrough the NMOS transistor Mb1 and current IB flowing through the NMOStransistor Mb2. The signal Smd is a signal (voltage) for switching theoperation mode. The signal Smd is transmitted from the logical controlcircuit 32. For example, the signal Smd is set to the Low (“L”) level inthe LP mode and is set to the High (“H”) level in the HP mode. When thesignal Smd is at the “L” level, the NMOS transistor Ms1 is turned off,and when the signal Smd is at the “H” level, the NMOS transistor Ms1 isturned on. Thus, in the LP mode, the bias current IA flows through thedifferential amplifier circuit 310, and in the HP mode, the bias currentIA+IB flows through the differential amplifier circuit 310. In addition,the transistor sizes of the NMOS transistors Mb1 and Mb2 are adjusted sothat the current IA and the current IB have a relationship of IA<IB.

The PMOS transistor M7 has one end connected to the node N1, the otherend connected to a node N8, and a gate connected to the node N4. Thatis, the PMOS transistor M7 is mirror-connected to the PMOS transistorM4.

The PMOS transistor M8 has one end connected to the node N1, the otherend connected to the node N10, and a gate connected to the node N3. Thatis, the PMOS transistor M8 is mirror-connected to the PMOS transistorM3.

The NMOS transistor Mb3 has one end connected to the node N8 and theother end connected to a node N9. A voltage VB2 is applied to a gate ofthe NMOS transistor Mb3.

The NMOS transistor Mb4 has one end connected to the node N10 and theother end connected to a node N11. The voltage VB2 is applied to a gateof the NMOS transistor Mb4.

The NMOS transistor M5 has one end connected to the node N9, the otherend connected to the node N2, and a gate connected to the node N8.

The NMOS transistor M6 has one end connected to the node N11, the otherend connected to the node N2, and a gate connected to the node N8.

That is, the NMOS transistors Mb3, Mb4, M5, and M6 configure a cascodecurrent mirror. The voltage VB2 is a bias voltage of the cascode currentmirror.

Next, the mode switching circuit 320 will be described. Since the biascurrent (IA or IA+IB) in the differential amplifier circuit 310 isdifferent between the LP mode and the HP mode, each potential in thedifferential amplifier circuit is different. Therefore, for example, thegate-source voltage of the NMOS transistors M1 and M2 which aredifferential pair transistors or the gate-source voltage of the NMOStransistor Mb4 which is a cascode device changes according to theoperation mode, so that the potential of the node N11 changes. The modeswitching circuit 320 generates (applies) the potential of the node N11in the HP mode in (or to) the node N15 in advance during the LP mode,and interconnects the node N11 and the node N15 at the timing ofswitching from the LP mode to the HP mode. The capacitor element C1having a relatively large capacitance is connected to the node N15.Therefore, the node N11 quickly changes to a voltage close to thevoltage generated in the node N15 due to charge sharing. Thereby, ascompared with a case where the mode switching circuit 320 is not used,the period from the start of switching from the LP mode to the HP modeuntil an operation of the HP mode is stabilized (hereinafter alsoreferred to as “HP stabilization period”) may be shortened.

The mode switching circuit 320 makes the potential of the node N15during the LP mode basically the same as the potential of the node N11in the HP mode. In addition, the potential of the node N15 may belowered to a drain voltage (voltage VDS) at which the transistor M6 mayoperate (ON state) in the HP mode. For example, when the potential ofthe node N15 is set lower than the potential of the node N11 in the HPmode, the undershoot of the output voltage VOUT generated after modeswitching may be improved. Similarly, when the potential of the node N15is set higher than the potential of the node N11 in the HP mode, theovershoot of the output voltage VOUT may be improved. Therefore, thepotential of the node N15 may be changed from the potential of the nodeN11 in the HP mode according to a required performance or the like.

For example, when the operation mode of the HP mode regulator 33 isswitched from the LP mode to the HP mode, the length of the HPstabilization period may depend on the stabilization of the terminalvoltage of the capacitor element C1, i.e., the charge/discharge periodof the capacitor element C1. Therefore, in the LP mode, the modeswitching circuit 320 according to the present embodiment generates theterminal voltage to be applied to the capacitor element C1 in the HPmode, and applies the generated voltage to the terminal of the capacitorelement C1 (charges the capacitor element C1) during the LP mode.Thereby, the charge/discharge period of the capacitor element C1 isshortened.

The mode switching circuit 320 includes PMOS transistors Msw3, Mb7, Mb8,and Msw6, and NMOS transistors Msw1, Msw2, Mb5, and Mb6.

The PMOS transistor Msw3 has one end connected to the node N1 and theother end connected to a node N12. The signal Smd is input to a gate.

The PMOS transistor Mb7 has one end connected to the node N12 and theother end connected to a node N13. A voltage VB3 is applied to a gate.

The PMOS transistor Mb8 has one end connected to the node N13 and theother end connected to a node N14. A voltage VB4 is applied to a gate.

The PMOS transistor Msw6 has one end connected to the node N1 and theother end connected to the node N10. The signal Smd is input to a gate.

The NMOS transistor Mb5 has one end connected to the node N14 and theother end connected to the node N15. The voltage VB2 is applied to agate.

The NMOS transistor Mb6 has one end connected to the node N15, the otherend connected to a node N16, and a gate connected to the node N14.

The NMOS transistor Msw2 has one end connected to the node N16 and theother end connected to the node N2. A signal SmdB which is an invertedsignal of the signal Smd is input to a gate.

The NMOS transistor Msw1 has one end connected to the node N11 and theother end connected to the node N15. The signal Smd is input to a gate.The NMOS transistor Msw1 functions as a switching element thatdisconnects the differential amplifier circuit 310 from the capacitorelement C1 in the LP mode.

For example, when the HP mode regulator 33 is in the LP mode, i.e., whenthe signal Smd is at the “L” level and the signal SmdB is at the “H”level, the NMOS transistor Msw1 is turned off, and the NMOS transistorMsw2 and the PMOS transistors Msw3 and Msw6 are turned on. In order togenerate the voltage in the HP mode in the node N15, a bias current isgenerated by the PMOS transistors Mb7 and Mb8, and a voltage to beapplied to the capacitor element C1 in the HP mode is generated by thevoltage VB2 and a voltage Vgs (gate-source voltage) of the NMOStransistor Mb5. Further, since the PMOS transistor Msw6 is turned on,the voltage VIN is applied to the gate of the PMOS transistor Mdrv. Thatis, the gate of the PMOS transistor Mdrv is connected to the node N1.Therefore, the PMOS transistor Mdrv is turned off. Accordingly, the HPmode regulator 33 does not operate as a regulator during the LP mode.

Further, for example, when the HP mode regulator 33 is in the HP mode,i.e., when the signal Smd is at the “H” level and the signal SmdB is atthe “L” level, the NMOS transistor Msw1 is turned on, and the NMOStransistor Msw2 and the PMOS transistors Msw3 and Msw6 are turned off.Thus, the node N11 and the node N15 are electrically connected to eachother. That is, the voltage of one side electrode of the capacitorelement C1 is applied to the node N11. Further, since the PMOStransistor Msw6 is turned off, the voltage of the node N10 is applied tothe PMOS transistor Mdrv.

The mode switching circuit 320 operates only in the LP mode, and nooperating current flows therethrough in the HP mode.

In addition, in the example of FIG. 5, the bias current is generated bythe PMOS transistors Mb7 and Mb8 in order to generate the voltage in theHP mode in the node N15, but the number of PMOS transistors is freelyselected.

1.1.6 Configuration of LP Mode Regulator

Next, an example of a configuration of the LP mode regulator 34 will bedescribed with reference to FIG. 6. FIG. 6 is a circuit diagramillustrating an example of a configuration of the LP mode regulator 34.

As illustrated in FIG. 6, the LP mode regulator 34 includes adifferential amplifier circuit 315, a PMOS transistor MLdrv, capacitorelements CL1 and CLOUT, resistance elements RLA and RLB, and terminalsTL1 and TL2.

The terminal TL1 functions as an input terminal at one side of thedifferential amplifier circuit 315. The reference voltage VREF_LP isinput to the terminal TL1 for constant voltage control by the LP moderegulator 34.

The terminal TL2 functions as an output terminal of the LP moderegulator 34. The voltage VOUT is output from the terminal TL2. Theterminal TL2 is connected to a node NL9 in the LP mode regulator 34.

The PMOS transistor MLdrv functions as an output driver of the LP moderegulator 34. In order to keep the output voltage VOUT of the LP moderegulator 34 constant, a gate voltage VLpg of the PMOS transistor MLdrvchanges according to the variation of the output voltage VOUT, so thatthe ON-resistance of the PMOS transistor MLdrv is adjusted. The PMOStransistor MLdrv has one end connected to a node NL1 (hereinafter, alsoreferred to as “power supply voltage wiring”) to which the voltage VIN(e.g., the voltage VCCQ_M) is applied and the other end connected to thenode NL9. A gate of the PMOS transistor MLdrv is connected to thedifferential amplifier circuit 315 via a node NL8, and the voltage VLpgis applied to the gate.

The resistance elements RLA and RLB function as a voltage dividingcircuit for the output voltage VOUT. The resistance element RLA has oneend connected to the node NL9 and the other end connected to a node NL6.The resistance element RLB has one end connected to the node NL6 and theother end connected to a node NL2 (hereinafter also referred to as“ground voltage wiring”) to which a ground voltage VSS is applied. Thevoltage applied to the node NL6 is VLD, the resistance value of theresistance element RLA is rLA, and the resistance value of theresistance element RLB is rLB. Then, a relationship between the outputvoltage VOUT and the voltage VLD is VLD=VOUT×(rLB/(rLA+rLB)).

The capacitor element CLOUT functions as an output capacitor. Thecapacitor element CLOUT has one side electrode connected to the node NL9and the other side electrode connected to the node NL2.

The capacitor element CL1 is provided for phase compensation of theoutput voltage VOUT. The capacitor element CL1 has one side electrodeconnected to a node NL5 and the other side electrode connected to thenode NL9. For example, for the capacitor element CL1, an element havinga relatively large capacitance is used for phase compensation.

The differential amplifier circuit 315 outputs a voltage VLpg dependingon the difference between the reference voltage VREF and the voltageVLD. The differential amplifier circuit 315 includes PMOS transistorsMLb1 and ML1 to ML4, and NMOS transistors MLb2 to MLb5.

The PMOS transistor MLb1 has one end connected to the node NL1 and theother end connected to a node NL3, and a voltage VLB1 is applied to agate. The voltage VLB1 is a bias voltage that controls the PMOStransistor MLb1.

The PMOS transistor ML1 has one end connected to the node NL3, the otherend connected to a node NL4, and a gate connected to the node NL6.

The PMOS transistor ML2 has one end connected to the node NL3 and theother end connected to the node NL5. A gate of the PMOS transistor ML2is connected to the terminal TL1, and the reference voltage VREF_LP isapplied to the gate.

The PMOS transistor ML3 has one end connected to the node NL1 and theother end and a gate which are connected to a node NL7.

The PMOS transistor ML4 has one end connected to the node NL1, the otherend connected to the node NL8, and a gate connected to the node NL7.That is, the PMOS transistors ML3 and ML4 are mirror-connected to eachother.

The NMOS transistor MLb2 has one end connected to the node NL7 and theother end connected to the node NL4. A voltage VLB2 is applied to a gateof the NMOS transistor MLb2.

The NMOS transistor MLb3 has one end connected to the node NL8 and theother end connected to the node NL5. The voltage VLB2 is applied to agate of the NMOS transistor MLb3. The voltage VLB2 is a bias voltagethat controls the NMOS transistors MLb2 and MLb3.

The NMOS transistor MLb4 has one end connected to the node NL4 and theother end connected to the node NL2. A voltage VLB3 is applied to a gateof the NMOS transistor MLb4.

The NMOS transistor MLb5 has one end connected to the node NL5 and theother end connected to the node NL2. The voltage VLB3 is applied to agate of the NMOS transistor MLb5. The voltage VLB3 is a bias voltagethat controls the NMOS transistors MLb4 and MLb5.

1.2 Voltage of Each Wiring of HP Mode Regulator

Next, the voltage of each wiring of the HP mode regulator 33 will bedescribed with reference to FIG. 7. FIG. 7 is a timing chartillustrating the voltage of each wiring of the HP mode regulator 33.

As illustrated in FIG. 7, first, at the time t0, the HP mode regulator33 starts switching from the LP mode to the HP mode. The period from thetime t0 to the time t4 corresponds to the HP stabilization period.

More specifically, at the time t0, the signal Smd that is the operationmode switching signal changes from the “L” level to the “H” level. Then,in the differential amplifier circuit 310, the bias current changes fromIA to IA+IB. Thereby, the nodes N3 and N4 start discharging. At a pointPp1 of the node N3, the voltage in the LP mode is Vp1_LP and the voltagein the HP mode is Vp1_HP. Then, the voltage Vp1_LP and the voltageVp1_HP have a relationship of Vp1_LP>Vp1_HP. Similarly, at a point Pp2of the node N4, the voltage in the LP mode is Vp2_LP and the voltage inthe HP mode is Vp2_HP. Then, the voltage Vp2_LP and the voltage Vp2_HPhave a relationship of Vp2_LP>Vp2_HP. More specifically, during theperiod until the time t0, i.e., in the LP mode, the voltage Vp1_LP andthe voltage Vp2_LP are applied to the points Pp1 and Pp2, respectively.Then, during the period from the time t0 to the time t2, the voltages atthe points Pp1 and Pp2 gradually decrease, and at the time t2, thevoltages at the points Pp1 and Pp2 reach the voltage Vp1_HP and thevoltage Vp2_HP, respectively.

As the voltage of the node N4 decreases, the current flowing through thePMOS transistor M7 increases and the node N8 is charged. At a point Pn1of the node N8, the voltage in the LP mode is Vn1_LP and the voltage inthe HP mode is Vn1_HP. Then, the voltage Vn1_LP and the voltage Vn1_HPhave a relationship of Vn1_LP<Vn1_HP. More specifically, the voltageVn1_LP is applied to the point Pn1 during the period until the time t0.Then, during the period from the time t0 to the time t3, the voltage atthe point Pn1 of the node N8 gradually increases, and at the time t3,the voltage at the point Pn1 reaches the voltage Vn1_HP.

In one side terminal connected to the node N11 of the capacitor elementC1, the voltage applied in the LP mode is Vc1_LP and the voltage appliedin the HP mode is Vc1_HP. Then, the voltage Vc1_LP and the voltageVc1_HP have a relationship of Vc1_LP>Vc1_HP. During the period until thetime t0, the voltage Vc1_LP is applied to a point PA of the node N11,and the voltage Vc1_HP is applied to a point PB of the node N15 of themode switching circuit 320. Further, the mode switching circuit 320applies the voltage Vc1_HP to the capacitor element C1. In thissituation, at the time t0, in the mode switching circuit 320, the NMOStransistor Msw1 is turned on and the NMOS transistor Msw2 and the PMOStransistors Msw3 and Msw6 are turned off. Therefore, the node N11 andthe node N15 are connected to each other. At this time, since the nodeN15 is connected to the capacitor element C1, the voltage at the pointPA of the node N11 and the voltage at the point PB of the node N15 arestabilized to approximately the voltage Vc1_HP by the time t1 due tocharge sharing.

At a point Ppg of the gate electrode of the PMOS transistor Mdrvconnected to the node N10, the voltage Vpg in the HP mode is Vpg_HP.Then, the voltage VIN and the voltage Vpg_HP have a relationship ofVIN>Vpg_HP.

At the time t1, the voltage at the point PB of the node N15 isstabilized to the voltage Vc1_HP. That is, when the source voltage ofthe NMOS transistor Mb4 decreases, current starts to flow from the nodeN10 to the node N11. Thereby, the voltage at the point Ppg of the nodeN10, i.e., the gate voltage Vpg of the PMOS transistor Mdrv decreasesfrom the voltage VIN to the voltage Vpg_HP during the period from thetime t1 to the time t4.

1.4 Effects of the Present Embodiment

With the configuration according to the present embodiment, it providesa semiconductor device that can improve processing capacity, as furtherdescribed below.

For example, the embodiment provides a semiconductor device including aregulator having both an LP mode and an HP mode that reduces powerconsumption during standby. The regulator is set to the LP mode when thesemiconductor device is in the standby state, and is switched to the HPmode when the semiconductor device shifts from the standby state to theactive state. In order to shorten the period until the semiconductordevice shifts to the active state, it is important to shorten theswitching time of the regulator from the LP mode to the HP mode.

In such a regulator, phase compensation is required, and therefore, acapacitor element having a relatively large capacitance is used. Theterminal voltage of the capacitor element in the LP mode and theterminal voltage of the capacitor element in the HP mode are different.Therefore, in many cases, for the length of the period for switching theoperation mode, the time during which the terminal voltage of thecapacitor element changes is dominant.

Meanwhile, with the configuration according to the present embodiment,the HP mode regulator 33 includes the mode switching circuit 320. Themode switching circuit 320 may apply the terminal voltage in the HP modeto the capacitor element C1 during the LP mode. Thereby, when switchingfrom the LP mode to the HP mode, the variation of the terminal voltageof the capacitor element C1 may be prevented. A delay in the switchingof the operation mode due to the variation of the terminal voltage ofthe capacitor element is prevented, and the stabilization period of theHP mode may be shortened. Accordingly, the processing capacity of thesemiconductor device may be improved.

Moreover, when the configuration according to the present embodiment isapplied to the memory system 1, the HP mode regulator 33 may be set tothe LP mode when the memory chip 10 does not operate, for example, whichmay reduce the current consumption of the memory system 1. Moreover, inthe power supply circuit 30, shifting from the LP mode to the HP modebecomes relatively fast (the HP stabilization period becomes relativelyshort). Therefore, the memory system 1 may shorten the period from thestart of shifting from the LP mode to the HP mode until an operation inthe HP mode may start. For example, the memory controller 20 may startcommunication with the memory chip 10 within a relatively short timeafter shifting to the HP mode, and the data transfer performance thereofis improved. Further, the memory controller 20 and the memory chip 10may start a data processing within a relatively short time aftershifting to the HP mode, and the data transfer performance/reliabilitythereof is improved. Further, since the stabilization period of the HPmode may be shortened, frequent shifting to the LP mode is possible evenwhen the standby state is kept for a relatively short time. Accordingly,the memory system 1 may reduce power consumption.

Moreover, the memory system 1 may include a plurality of memory chips10. The plurality of memory chips 10 are divided into a memory chip 10that is in the access state (i.e., that is in the active state) withrespect to the memory controller 20 and a memory chip 10 that is not inthe access state (i.e., that is in the standby state). In such a case,the memory system 1 to which the configuration according to the presentembodiment is applied may individually and rapidly switch the operationmode of each memory chip 10 according to the state. Accordingly, thememory system 1 may reduce power consumption.

2. Second Embodiment

Next, a second embodiment will be described. In the second embodiment,six examples of a configuration of the HP mode regulator 33 differentfrom the first embodiment will be described. Hereinafter, differencesfrom the first embodiment will be mainly described.

2.1 First Example

A first example will be described. In this example, a case where themode switching circuit 320 is applied to the PMOS transistor Mdrv havinga large gate capacitance will be described.

2.1.1 Configuration of HP Mode Regulator

An example of a configuration of the HP mode regulator 33 according tothe first example will be described with reference to FIG. 8. FIG. 8illustrates an example of a circuit diagram of the HP mode regulator 33.The HP mode regulator 33 of this example is different from the firstembodiment in the configuration of the mode switching circuit 320.

As illustrated in FIG. 8, the HP mode regulator 33 includes theterminals T1 and T2, the resistance elements RA and RB, the capacitorelements C1 and COUT, the PMOS transistor Mdrv, the differentialamplifier circuit 310, and the mode switching circuit 320.

The connection sites of the terminals T1 and T2, the capacitor elementCOUT, and the resistance elements RA and RB are the same as in FIG. 5 ofthe first embodiment.

The capacitor element C1 has one side electrode connected to the nodeN11, i.e., the differential amplifier circuit 310 and the other sideelectrode connected to the node N17.

The PMOS transistor Mdrv has one end connected to the node N1 and theother end connected to a node N18. The gate of the PMOS transistor Mdrvis connected to the node N13, and the voltage Vpg is applied to thegate.

The configuration of the differential amplifier circuit 310 is the sameas in FIG. 5 of the first embodiment.

The mode switching circuit 320 includes PMOS transistors Msw1′, Msw3,Msw4, Mb7, Mb8, and Msw6, and NMOS transistors Msw1, Msw2, Mb5, and Mb6.

Each of the PMOS transistor Msw1′ and the NMOS transistor Msw1 has oneend connected to the node N10 and the other end connected to the nodeN13. The signal SmdB is input to a gate of the PMOS transistor Msw1′.The signal Smd is input to the gate of the NMOS transistor Msw1. ThePMOS transistor Msw1′ and the NMOS transistor Msw1 function as a CMOSanalog switch. The gate electrode of the PMOS transistor Mdrv isseparated from the differential amplifier circuit 310 in the LP mode bythe PMOS transistor Msw1′ and the NMOS transistor Msw1.

The PMOS transistor Msw3 has one end connected to the node N1 and theother end connected to the node N12. The signal Smd is input to thegate.

The PMOS transistor Mb7 has one end connected to the node N12, the otherend connected to the node N13, and the gate connected to the node N14.

The PMOS transistor Mb8 has one end connected to the node N13 and theother end connected to the node N14. The voltage VB3 is applied to thegate.

The PMOS transistor Msw6 has one end connected to the node N1 and theother end connected to the node N10. The signal Smd is input to thegate.

The NMOS transistor Mb5 has one end connected to the node N14 and theother end connected to the node N15. A voltage VB4 is applied to thegate.

The NMOS transistor Mb6 has one end connected to the node N15 and theother end connected to the node N16. A voltage VB5 is applied to thegate.

The NMOS transistor Msw2 has one end connected to the node N16 and theother end connected to the node N2. The signal SmdB is input to thegate.

The PMOS transistor Msw4 has one end connected to the node N18 and theother end connected to the node N17. The signal SmdB is input to thegate.

For example, when the HP mode regulator 33 is in the LP mode, i.e., whenthe signal Smd is at the “L” level and the signal SmdB is at the “H”level, the mode switching circuit 320 applies the voltage in the HP modeto the node N13. That is, the voltage Vpg_HP in the HP mode is appliedto the gate of the PMOS transistor Mdrv. Further, the mode switchingcircuit 320 applies the voltage VIN to the node N10.

Further, for example, when the HP mode regulator 33 is in the HP mode,i.e., when the signal Smd is at the “H” level and the signal SmdB is atthe “L” level, the mode switching circuit 320 electrically interconnectsthe node N10 and the node N13 of the differential amplifier circuit 310.That is, the voltage of the node N10 is applied to the gate of the PMOStransistor Mdrv.

2.1.2 Voltage of Each Wiring of HP Mode Regulator

Next, the voltage of each wiring of the HP mode regulator 33 will bedescribed with reference to FIG. 9. FIG. 9 is a timing chartillustrating the voltage of each wiring of the HP mode regulator 33.

As illustrated in FIG. 9, first, at the time t0, the HP mode regulator33 starts switching from the LP mode to the HP mode. The period from thetime t0 to the time t3 corresponds to the HP stabilization period.

The signal Smd and the voltage variation at the points Pp1, Pp2, and Pn1are the same as in FIG. 7 of the first embodiment. In this example, oneside electrode of the capacitor element C1 is connected to the node N11.

During the period until the time t0, the voltage VIN is applied to apoint PC of the node N10, and the voltage Vpg_HP is applied from themode switching circuit 320 to the point Ppg. Then, when the PMOStransistor Msw1′ and the NMOS transistor Msw of the mode switchingcircuit 320 are turned on at the time t0, the node N10 and the node N13are connected to each other. At this time, since the node N13 isconnected to the PMOS transistor Mdrv, the voltage at the point PC ofthe node N10 is stabilized to approximately the voltage Vpg_HP by timet1 due to charge sharing.

2.2 Second Example

Next, a second example will be described. In this example, a case wherea VOUT load current circuit is added to the HP mode regulator 33 of thefirst example of the second embodiment will be described. Hereinafter,differences from the first example of the second embodiment will bemainly described.

2.2.1 Configuration of HP Mode Regulator

An example of a configuration of the HP mode regulator 33 according tothe second example will be described with reference to FIG. 10. FIG. 10illustrates an example of a circuit diagram of the HP mode regulator 33.

As illustrated in FIG. 10, the HP mode regulator 33 includes theterminals T1 and T2, the resistance elements RA and RB, the capacitorelements C1 and COUT, the PMOS transistor Mdrv, the differentialamplifier circuit 310, the mode switching circuit 320, and a VOUT loadcurrent circuit 330.

The connections and configurations of the terminals T1 and T2, theresistance elements RA and RB, the capacitor elements C1 and COUT, thePMOS transistor Mdrv, the differential amplifier circuit 310, and themode switching circuit 320 are the same as in FIG. 8 of the firstexample of the second embodiment.

For example, the load current of the output voltage VOUT may be unknownimmediately after switching from the LP mode to the HP mode. The VOUTload current circuit 330 may flow preset constant current Irout thereinin the HP mode. Thereby, the minimum value of the load current of theoutput voltage VOUT may be set.

The VOUT load current circuit 330 sets the minimum value of the loadcurrent and the load current range at the terminal T2. The VOUT loadcurrent circuit 330 includes a resistance element ROUT and an NMOStransistor Msw5.

The resistance element ROUT has one end connected to the node N17 andthe other end connected to a node N19.

The NMOS transistor Msw5 has one end connected to the node N19 and theother end connected to the node N2. The signal Smd is input to a gate ofthe NMOS transistor Msw5.

The NMOS transistor Msw5 of the VOUT load current circuit 330 is turnedoff in the LP mode and is turned on in the HP mode. Therefore, assumingthat the resistance value of the resistance element ROUT is rOUT,constant current Irout (=VOUT/rOUT) flows from the node N17 to the nodeN2 during the HP mode.

2.2.2 Voltage and Current of Each Wiring of HP Mode Regulator

Next, the voltage and current of each wiring of the HP mode regulator 33will be described with reference to FIG. 11. FIG. 11 is a timing chartillustrating the voltage and current of each wiring of the HP moderegulator 33.

As illustrated in FIG. 11, first, at the time t0, the HP mode regulator33 starts switching from the LP mode to the HP mode. The period from thetime t0 to the time t3 corresponds to the HP stabilization period.

The signal Smd and the voltage variation at the points Pp1, Pp2, Pn1,PC, and Ppg are the same as in FIG. 9 of the first example of the secondembodiment.

During the period until the time t0, the NMOS transistor Msw5 is in theoff state, so that no current flows to the node N19 of the VOUT loadcurrent circuit 330. Then, when the NMOS transistor Msw5 is turned on atthe time t0, the current Irout flows to the node N19 of the VOUT loadcurrent circuit 330.

2.3 Third Example

Next, a third example will be described. In this example, a case where aphase compensation circuit 340 is added to the HP mode regulator 33 ofthe first example of the second embodiment will be described.Hereinafter, differences from the first example of the second embodimentwill be mainly described.

2.3.1 Configuration of HP Mode Regulator

An example of a configuration of the HP mode regulator 33 according tothe third example will be described with reference to FIG. 12. FIG. 12illustrates an example of a circuit diagram of the HP mode regulator 33.

As illustrated in FIG. 12, the HP mode regulator 33 includes theterminals T1 and T2, the resistance elements RA and RB, the capacitorelements C1 and COUT, the PMOS transistor Mdrv, the differentialamplifier circuit 310, the mode switching circuit 320, and the phasecompensation circuit 340.

The connections and configurations of the terminals T1 and T2, theresistance elements RA and RB, the capacitor elements C1 and COUT, thePMOS transistor Mdrv, the differential amplifier circuit 310, and themode switching circuit 320 are the same as in FIG. 8 of the firstexample of the second embodiment.

The phase compensation circuit 340 is provided as phase compensation forthe gate of the PMOS transistor Mdrv. The phase compensation circuit 340includes a capacitor element C2 and a resistance element R2.

The phase compensation circuit 340 interconnects the node N1 and thenode N13 in the vicinity of the PMOS transistor Mdrv. More specifically,the capacitor element C2 has one side electrode connected to the node N1and the other side electrode connected to one end of the resistanceelement R2. The other end of the resistance element R2 is connected tothe node N13.

Accordingly, the phase compensation circuit 340 is connected between ananalog switch implemented by the PMOS transistor Msw1′ and the NMOStransistor Msw1 of the mode switching circuit 320 and the PMOStransistor Mdrv.

In addition, the voltage of each wiring of the HP mode regulator 33 inthis example is the same as in FIG. 9 of the first example of the secondembodiment.

2.4 Fourth Example

Next, a fourth example will be described. In this example, aconfiguration of the HP mode regulator 33 when the capacitance of thecapacitor element C2 of the phase compensation circuit 340 of the thirdexample of the second embodiment is greater than the gate capacitance ofthe PMOS transistor Mdrv will be described. Hereinafter, differencesfrom the third example of the second embodiment will be mainlydescribed.

2.4.1 Configuration of HP Mode Regulator

An example of a configuration of the HP mode regulator 33 according tothe fourth example will be described with reference to FIG. 13. FIG. 13illustrates an example of a circuit diagram of the HP mode regulator 33.

As illustrated in FIG. 13, the HP mode regulator 33 includes theterminals T1 and T2, the resistance elements RA and RB, the capacitorelements C1 and COUT, the PMOS transistor Mdrv, the differentialamplifier circuit 310, the mode switching circuit 320, and the phasecompensation circuit 340.

The connections and configurations of the terminals T1 and T2, theresistance elements RA and RB, the capacitor elements C1 and COUT, thedifferential amplifier circuit 310, the mode switching circuit 320, andthe phase compensation circuit 340 are the same as in the third exampleof the second embodiment.

The PMOS transistor Mdrv has one end connected to the node N1 and theother end connected to the node N18. The gate of the PMOS transistorMdrv is connected to the node N10, and the voltage Vpg is applied to thegate.

In this example, an analog switch implemented by the PMOS transistorMsw1′ and the NMOS transistor Msw1 of the mode switching circuit 320 isdisposed between the phase compensation circuit 340 and the PMOStransistor Mdrv.

2.4.2 Voltage of Each Wiring of HP Mode Regulator

Next, the voltage of each wiring of the HP mode regulator 33 will bedescribed with reference to FIG. 14. FIG. 14 is a timing chartillustrating the voltage of each wiring of the HP mode regulator 33.

As illustrated in FIG. 14, first, at the time t0, the HP mode regulator33 starts switching from the LP mode to the HP mode. The period from thetime t0 to the time t3 corresponds to the HP stabilization period.

The signal Smd and the voltage variation at the points Pp1, Pp2, and Pn1are the same as in FIG. 9 of the first example of the second embodiment.

During the period until the time t0, the voltage Vpg_HP is applied to apoint PD of the node N13. Then, when the PMOS transistor Msw1′ and theNMOS transistor Msw of the mode switching circuit 320 are turned on atthe time t0, the node N10 and the node N13 are connected to each other.At this time, since the node N13 is connected to the capacitor elementC2, the voltage at the point Ppg is stabilized to approximately thevoltage Vpg_HP by time t1 due to the charge sharing.

2.5 Fifth Example

Next, a fifth example will be described. In this example, a case where aboost circuit 350 is added to the HP mode regulator 33 of the firstembodiment will be described.

2.5.1 Configuration of HP Mode Regulator

An example of a configuration of the HP mode regulator 33 according tothe fifth example will be described with reference to FIG. 15. FIG. 15illustrates an example of a circuit diagram of the HP mode regulator 33.

As illustrated in FIG. 15, the HP mode regulator 33 includes theterminals T1 and T2, the resistance elements RA and RB, the capacitorelements C1, COUT, a capacitor element CB4, the PMOS transistor Mdrv,the differential amplifier circuit 310, the mode switching circuit 320,and the boost circuit 350.

The connections and configurations of the terminals T1 and T2, theresistance elements RA and RB, the capacitor elements C1 and COUT, thedifferential amplifier circuit 310, and the mode switching circuit 320are the same as in FIG. 5 of the first embodiment.

The capacitor element CB4 has one side electrode connected to a node N20and the other side electrode connected to the node N2. The capacitorelement CB4 is provided in order to make the voltage variation at apoint PE of the node N20 relatively gentle by the charge and dischargeof the capacitor element CB4.

The boost circuit 350 boosts the bias current IA+IB flowing through thedifferential amplifier circuit 310 within a relatively short periodimmediately after the HP mode regulator 33 is switched from the LP modeto the HP mode in order to shorten the HP stabilization period.

The boost circuit 350 includes a current source 360 and NMOS transistorsM10 to M13.

The current source 360 has an input terminal connected to the node N1and an output terminal connected to the node N20.

The NMOS transistor M10 has one end and a gate which are connected tothe node N20 and the other end connected to a node N21. The node N20 isconnected to the gates of the NMOS transistors Mb1 and Mb2 in thedifferential amplifier circuit 310. That is, the bias voltage VB1 isapplied to the gates of the NMOS transistors Mb1 and Mb2 via the nodeN20.

The NMOS transistor M11 has one end connected to the node N21, the otherend connected to a node N22, and a gate connected to the node N20.

The NMOS transistor M12 has one end connected to the node N22, the otherend connected to the node N2, and a gate connected to the node N20.

The NMOS transistor M13 has one end connected to the node N22 and theother end connected to the node N2. A signal BSTENB is applied to a gateof the NMOS transistor M13. The signal BSTENB is a signal for boostcontrolling the bias current IA+IB. For example, the signal BSTENB isset to the “L” level while boosting the bias current IA+IB in the HPmode, and is switched from the “L” level to the “H” level when the boostof the bias current IA+IB ends.

The signal BSTENB is transmitted from, for example, the logical controlcircuit 32.

2.5.2 Voltage and Current of Each Wiring of HP Mode Regulator

Next, the voltage and current of each wiring of the HP mode regulator 33will be described with reference to FIG. 16. FIG. 16 is a timing chartillustrating the voltage and current of each wiring of the HP moderegulator 33. In the example of FIG. 16, a case where there is boost ofthe bias current IA+IB by the boost circuit 350 is represented by asolid line, and a case where there is no boost (i.e., a case of showingthe same behavior as in the first embodiment) is represented by a dashedline.

As illustrated in FIG. 16, first, at the time t0, the HP mode regulator33 starts switching from the LP mode to the HP mode. In this example,the period from time the t0 to the time t5 corresponds to the HPstabilization period.

For example, during the period until the time t0, i.e., in the LP mode,the signal BSTENB is set to the “L” level. In this case, the boostcircuit 350 is in the boost state. At the point PE of the node N20, thevoltage VB1 when the boost circuit 350 is in the boost state is VB1_BST,and the voltage VB1 when the boost circuit 350 is in the non-boost state(normal state in the HP mode) is VB1 HP. Then, the voltage VB1_BST andthe voltage VB1 HP have a relationship of VB1_BST>VB1 HP. Accordingly,the voltage VB1_BST is applied to the point PE during the LP mode.

However, because the signal Smd is at the “L” level during the LP mode,the NMOS transistor Ms1 of the differential amplifier circuit 310 isturned off. Therefore, the bias current IA (boosted bias current IA)flows through the differential amplifier circuit 310. In addition, thesignal BSTENB may be set to the “H” level during the LP mode.

When the signal Smd is set to the “H” level at the time t0, the NMOStransistor Ms1 of the differential amplifier circuit 310 is turned on.Therefore, the differential amplifier circuit 310 boosts the biascurrent IA+IB. The bias current IA+IB in the boost state is expressed asI_BST, and the bias current IA+IB in the normal state in the HP mode isexpressed as I_HP. Then, the current I_BST and the current I_HP have arelationship of I_BST>I_HP. When the signal Smd is set to the “H” level,the bias current I_BST flows through the differential amplifier circuit310.

When the bias current I_BST flows through the differential amplifiercircuit 310, the period until the voltage Vpg is stabilized isshortened. That is, the HP stabilization period is shortened.

For example, the voltages at the points Pp1 and Pp2 change respectivelyfrom the voltage Vp1_LP and the voltage Vp2_LP to the voltage Vp1_HP andthe voltage Vp2_HP during the period from the time t0 to the time t6when there is no boost. Meanwhile, when there is boost, the voltages atthe points Pp1 and Pp2 change respectively from the voltage Vp1_LP andthe voltage Vp2_LP to a voltage Vp1_HP′ and a voltage Vp2_HP′ which areslightly lower than the voltage Vp1_HP and the voltage Vp2_HP during theperiod from the time t0 to the time t3, and is stable during the periodfrom the time t3 to the time t9. Then, when shifting from the booststate to the non-boost state during the period from the time t9 to thetime t10, the voltages Vp1_HP′ and the voltage Vp2_HP′ at the points Pp1and Pp2 change to the voltage Vp1_HP and the voltage Vp2_HP,respectively.

For example, the voltage at the point Pn1 changes from the voltageVn1_LP to the voltage Vn1_HP during the period from the time t0 to thetime t7 when there is no boost. Meanwhile, when there is boost, thevoltage at the point Pn1 changes from the voltage Vn1_LP to a voltageVn1_HP′ which is slightly higher than the voltage Vn1_HP during theperiod from the time t0 to the time t4, and is stable during the periodfrom the time t4 to the time t9. Then, when shifting from the booststate to the non-boost state during the period from the time t9 to thetime t10, the voltage Vn1_HP′ at the point Pn1 changes to the voltageVn1_HP.

For example, when there is no boost, the voltages at the points PA andPB are stabilized to the voltage Vc1_HP at the time t2 after chargesharing. Meanwhile, when there is boost, the voltages at the points PAand PB are stabilized to a voltage Vc1_HP′ which is slightly lower thanthe voltage Vc1_HP at the time t2 after charge sharing. Then, whenshifting from the boost state to the non-boost state during the periodfrom the time t9 to the time t10, the voltage Vc1_HP′ at the points PAand PB changes to the voltage Vc1_HP.

For example, the voltage at the point Ppg changes from the voltageVpg_LP to the voltage Vpg_HP during the period from the time t1 to thetime t8 when there is no boost. Meanwhile, when there is boost, thevoltage at the point Ppg changes from the voltage Vpg_LP to the voltageVpg_HP during the period from the time t1 to the time t5.

The signal BSTENB is switched from the “L” level to the “H” level at thetime t9 after, for example, the voltages at the points Pp1, Pp2, Pn1,PA, PB, and Ppg are stabilized. Thereby, the boost circuit 350 ends theboost state. Therefore, the voltage at the point PE changes from thevoltage VB1_BST to the voltage VB1 HP during the period from the time t9to the time t10. At this time, the voltage at the point PE decreasesrelatively gently due to the influence of the capacitor element CB4.Similarly, the bias current IA+IB also decreases relatively gently(smoothly) from the current I_BST to the current I_HP during the periodfrom the time t9 to the time t10. By changing the amount of bias currentgently, it is possible to follow each potential of the HP mode regulator33. Therefore, the HP mode regulator 33 may switch the bias currentIA+IB in the normal operation state of the HP mode.

2.6 Sixth Example

Next, a sixth example will be described. In this example, a case wherethe boost circuit 350 described in the fifth example of the secondembodiment is applied to the VOUT load current circuit 330 will bedescribed. Hereinafter, differences from the second example and thefifth example of the second embodiment will be mainly described.

2.6.1 Configuration of HP Mode Regulator

An example of a configuration of the HP mode regulator 33 according tothe sixth example will be described with reference to FIG. 17. FIG. 17illustrates an example of a circuit diagram of the HP mode regulator 33.

As illustrated in FIG. 17, the HP mode regulator 33 includes theterminals T1 and T2, the resistance elements RA and RB, the capacitorelements C1, COUT, and CB4, the PMOS transistor Mdrv, the differentialamplifier circuit 310, the mode switching circuit 320, and the VOUT loadcurrent circuit 330, and the boost circuit 350.

The connections and configurations of the terminals T1 and T2, theresistance elements RA and RB, the capacitor elements C1 and COUT, thePMOS transistor Mdrv, the differential amplifier circuit 310, and themode switching circuit 320 are the same as in the second example of thesecond embodiment illustrated in FIG. 10.

The capacitor element CB4 of this example has one side electrodeconnected to a node N24 and the other side electrode connected to thenode N2.

The VOUT load current circuit 330 of this example includes NMOStransistors Mbb1 and Mbb2.

The NMOS transistor Mbb1 has one end connected to the node N17 and theother end connected to a node N23. A bias voltage VB6 generated by theboost circuit 350 is applied to a gate of the NMOS transistor Mbb1.

The NMOS transistor Mbb2 has one end connected to the node N23 and theother end connected to the node N2. The signal Smd is input to the gateof the NMOS transistor Mbb2. For example, when the signal Smd is at the“L” level, i.e., in the LP mode, the NMOS transistor Mbb2 is turned off.Therefore, output current IOUT does not flow through the VOUT loadcurrent circuit 330.

To shorten the HP stabilization period, the boost circuit 350 of thisexample boosts the voltage VB6 to be applied to the VOUT load currentcircuit 330 within a relatively short period immediately after the HPmode regulator 33 is switched from the LP mode to the HP mode.

The boost circuit 350 includes the current source 360 and NMOStransistors Mbb3 to Mbb6. The configurations of the NMOS transistorsMbb3 to Mbb6 are the same as the NMOS transistors M10 to M13 of theboost circuit 350 described in FIG. 15 of the fifth example of thesecond embodiment.

More specifically, the current source 360 has an input terminalconnected to the node N1 and an output terminal connected to the nodeN24.

The NMOS transistor Mbb3 has one end and a gate which are connected tothe node N24 and the other end connected to a node N25.

The NMOS transistor Mbb4 has one end connected to the node N25, theother end connected to a node N26, and a gate connected to the node N24.

The NMOS transistor Mbb5 has one end connected to the node N26, theother end connected to the node N2, and a gate connected to the nodeN24.

The NMOS transistor Mbb6 has one end connected to the node N26 and theother end connected to the node N2. The signal BSTENB is applied to agate of the NMOS transistor Mbb6. The signal BSTENB is a signal forboost controlling the bias voltage VB6. For example, the signal BSTENBis set to the “L” level in the HP mode while boosting the bias voltageVB6, and is switched from the “L” level to the “H” level when ending theboost of the output current IOUT.

2.6.2 Voltage and Current of Each Wiring of HP Mode Regulator

Next, the voltage and current of each wiring of the HP mode regulator 33will be described with reference to FIG. 18. FIG. 18 is a timing chartillustrating the voltage and current of each wiring of the HP moderegulator 33.

As illustrated in FIG. 18, first, at the time t0, the HP mode regulator33 starts switching from the LP mode to the HP mode. In this example,the period from the time t0 to the time t5 corresponds to the HPstabilization period.

For example, during the period until the time t0, i.e., in the LP mode,the signal BSTENB is set to the “L” level. In this case, the boostcircuit 350 is in the boost state. At a point PF of the node N24, thevoltage VB6 when the boost circuit 350 is in the boost state is VB6_BSTand the voltage VB6 when the boost circuit 350 is in the non-boost state(normal state in the HP mode) is VB6_HP. Then, the voltage VB6_BST andthe voltage VB6_HP have a relationship of VB6_BST>VB6_HP. Thus, thevoltage VB6_BST is applied to the point PE during the LP mode.

However, since the signal Smd is at the “L” level during the LP mode,the NMOS transistor Mbb2 of the VOUT load current circuit 330 is turnedoff. Therefore, the output current IOUT does not flow through the VOUTload current circuit 330. In addition, the signal BSTENB may be set tothe “H” level during the LP mode.

The voltage variation at the points Pp1, Pp2, Pn1, PC, and Ppg are thesame as in the period from the time t0 to the time t3 in FIG. 9 of thesecond example of the second embodiment.

More specifically, the voltages at the points Pp1 and Pp2 change fromthe voltage Vp1_LP and the voltage Vp2_LP to the voltage Vp1_HP and thevoltage Vp2_HP during the period from the time t0 to the time t2,respectively.

The voltage at the point Pn1 changes from the voltage Vn1_LP to thevoltage Vn1_HP during the period from the time t0 to the time t3.

During the period until the time t0, the voltage VIN is applied to thepoint PC of the node N10, and the voltage Vpg_HP is applied to the pointPpg. Then, at the time t0, the node N10 and the node N13 are connectedto each other. At this time, the voltage at the point PC is stabilizedto approximately the voltage Vpg_HP by time t1 due to charge sharingwith the node N13 connected to the PMOS transistor Mdrv.

The signal BSTENB is switched from the “L” level to the “H” level at thetime t4 after, for example, the voltages at the points Pp1, Pp2, Pn1,PC, and Ppg are stabilized. Thereby, the boost circuit 350 ends theboost state. Therefore, the voltage at the point PF changes from thevoltage VB6_BST to the voltage VB6_HP during the period from the time t4to the time t5. At this time, the voltage at the point PF decreasesrelatively gently due to the influence of the capacitor element CB4.Similarly, the output current IOUT also decreases relatively gently fromthe current I_BST to the current I_HP during the period from the time t4to the time t5. By gently changing the output current IOUT, thevariation of the output voltage VOUT of the HP mode regulator 33 may beprevented.

2.7 Effects of the Present Embodiment

With the configuration according to the present embodiment, the sameeffects as those of the first embodiment may be obtained.

With the configuration according to the first example of the presentembodiment, the HP mode regulator 33 may apply the voltage Vpg_HP in theHP mode to the gate of the PMOS transistor Mdrv during the LP mode.Thereby, when the charge/discharge period of the gate capacitance of thePMOS transistor Mdrv is dominant for the length of the HP stabilizationperiod, the variation of the gate capacitance of the PMOS transistorMdrv may be prevented, and the HP stabilization period may be shortened.

With the configuration according to the second example of the presentembodiment, the HP mode regulator 33 includes the VOUT load currentcircuit 330. For example, the load current of the output voltage VOUTmay be unknown immediately after switching from the LP mode to the HPmode. Meanwhile, the VOUT load current circuit 330 may flow the presetconstant current Irout therethrough in the HP mode. Thereby, the minimumvalue of the load current of the output voltage VOUT may be set.

With the configuration according to the third example of the presentembodiment, the HP mode regulator 33 includes the phase compensationcircuit 340 connected to the gate of the PMOS transistor Mdrv which isthe output transistor. For example, in case of a regulator having nomode switching circuit 320, when the phase compensation circuit 340 isprovided, the gate capacitance of the output transistor becomes large,and therefore, the HP stabilization period tends to be increased. Whenthis time is dominant for the length of the HP stabilization period,this example may prevent the HP stabilization period from beingincreased according to the variation of the gate capacitance of the PMOStransistor Mdrv by combining the phase compensation circuit 340 with themode switching circuit 320.

With the configuration according to the fourth example of the presentembodiment, the HP mode regulator 33 may apply the voltage Vpg_HP in theHP mode to the capacitor element C2 of the phase compensation circuit340 during the LP mode. Thereby, when the charge/discharge period of thecapacitor element C2 is dominant for the length of the HP stabilizationperiod, the capacitance variation of the capacitor element C2 may beprevented and the HP stabilization period may be shortened.

With the configuration according to the fifth example of the presentembodiment, the HP mode regulator 33 may boost the bias current IA+IB inthe differential amplifier circuit 310 when switching from the LP modeto the HP mode. Thereby, the period until the voltage of each node isstabilized may be shorted. This may shorten the HP stabilization period.

The sixth example of the present embodiment can obtain the same effectas that of the second example of the present embodiment. Moreover, theHP mode regulator 33 may boost the output current IOUT when switchingfrom the LP mode to the HP mode. Thereby, the variation of the outputvoltage VOUT of the HP mode regulator 33 may be prevented.

3. Third Embodiment

Next, a third embodiment will be described. In the third embodiment, acase where one regulator circuit corresponds to the HP mode and the LPmode will be described. Hereinafter, differences from the first andsecond embodiments will be mainly described.

3.1 Configuration of Power Supply Circuit 30

First, a configuration of the power supply circuit 30 will be describedwith reference to FIG. 19. FIG. 19 is a block diagram illustrating anexample of a configuration of the power supply circuit 30. The powersupply circuit 30 included in the memory chip 10 will be describedbelow, but the power supply circuit 30 included in the memory controller20 is the same.

As illustrated in FIG. 19, the power supply circuit includes thereference voltage generation circuit 31, the logical control circuit 32,and an HP/LP mode regulator 35.

The reference voltage generation circuit 31 is supplied with, forexample, the voltage VCCQ_M (in case of the memory controller 20, thevoltage VCCQ_C). The reference voltage generation circuit 31 suppliesthe reference voltage VREF to the HP/LP mode regulator 35.

The logical control circuit 32 transmits a switching signal Smd (SmdB)between the HP mode and the LP mode and various control signals to theHP/LP mode regulator 35.

The HP/LP mode regulator 35 is a regulator used in the HP mode and theLP mode. The HP/LP mode regulator 35 outputs the voltage VOUT. Detailsthereof will be described below.

3.2 Configuration of HP/LP Mode Regulator

Next, an example of a configuration of the HP/LP mode regulator 35 willbe described with reference to FIG. 20. FIG. 20 illustrates an exampleof a circuit diagram of the HP/LP mode regulator 35.

As illustrated in FIG. 20, the HP/LP mode regulator 35 includes theterminals T1 and T2, the resistance elements RA and RB, the capacitorelements C1 and COUT, the PMOS transistor Mdrv, a PMOS transistor Mdrv2,the differential amplifier circuit 310, and the mode switching circuit320.

The connections and configurations of the terminals T1 and T2, theresistance elements RA and RB, the capacitor elements C1 and COUT, thePMOS transistor Mdrv, and the differential amplifier circuit 310 are thesame as in FIG. 8 of the first example of the second embodiment.

The PMOS transistor Mdrv functions as an HP mode output driver.Meanwhile, the PMOS transistor Mdrv2 functions as an LP mode outputdriver. The PMOS transistor Mdrv2 has one end connected to the node N1and the other end connected to the node N17. A gate of the PMOStransistor Mdrv2 is connected to the node N10.

The mode switching circuit 320 has the same configuration as in thefirst example of the second embodiment illustrated in FIG. 8 except thatthe PMOS transistor Msw6 is omitted. More specifically, the modeswitching circuit 320 includes the PMOS transistors Msw1′, Msw3, Msw4,Mb7, and Mb8, and the NMOS transistors Msw1, Msw2, Mb5, and Mb6.

Each of the PMOS transistor Msw1′ and the NMOS transistor Msw1 has oneend connected to the node N10 and the other end connected to the nodeN13. The signal SmdB is input to the gate of the PMOS transistor Msw1′.The signal Smd is input to the gate of the NMOS transistor Msw1. ThePMOS transistor Msw1′ and the NMOS transistor Msw1 function as a CMOSanalog switch. In the LP mode, the gate electrode of the PMOS transistorMdrv is separated from the differential amplifier circuit 310 by thePMOS transistor Msw1′ and the NMOS transistor Msw1.

The PMOS transistor Msw3 has one end connected to the node N1 and theother end connected to the node N12. The signal Smd is input to thegate.

The PMOS transistor Mb7 has one end connected to the node N12, the otherend connected to the node N13, and the gate connected to the node N14.

The PMOS transistor Mb8 has one end connected to the node N13 and theother end connected to the node N14. The voltage VB3 is applied to thegate.

The PMOS transistor Msw6 has one end connected to the node N1 and theother end connected to the node N10. The signal Smd is input to thegate.

The NMOS transistor Mb5 has one end connected to the node N14 and theother end connected to the node N15. The voltage VB4 is applied to thegate.

The NMOS transistor Mb6 has one end connected to the node N15 and theother end connected to the node N16. The voltage VB5 is applied to thegate.

The NMOS transistor Msw2 has one end connected to the node N16 and theother end connected to the node N2. The signal SmdB is input to thegate.

The PMOS transistor Msw4 has one end connected to the node N18 and theother end connected to the node N17. The signal SmdB is input to thegate.

3.3 Voltage of Each Wiring of HP/LP Mode Regulator

Next, the voltage of each wiring of the HP/LP mode regulator 35 will bedescribed with reference to FIG. 21. FIG. 21 is a timing chartillustrating the voltage of each wiring of the HP/LP mode regulator 35.

As illustrated in FIG. 21, first, at the time t0, the HP/LP moderegulator 35 starts switching from the LP mode to the HP mode. Theperiod from the time t0 to the time t3 corresponds to the HPstabilization period.

The signal Smd and the voltage variation at the points Pp1, Pp2, Pn1,and Ppg are the same as in FIG. 9 of the first example of the secondembodiment.

Unlike FIG. 9 of the first example of the second embodiment, in thisexample, a voltage Vpg2_LP is applied from the differential amplifiercircuit 310 to the point PC of the node N10 during the period until thetime t0. For example, in the example of FIG. 9, the voltage Vpg_LPhaving a potential close to the voltage VIN is applied to the point PCuntil the time t0. Meanwhile, in this example, the voltage Vpg2_LP isapplied to the point PC. The voltage Vpg2_LP is a voltage applied to apoint Ppg2 of the gate electrode of the PMOS transistor Mdrv2 in the LPmode. The voltage Vpg2_LP has a potential determined by the gate-sourcevoltage Vgs of the PMOS transistor Mdrv2. Accordingly, for example, thevoltage Vpg_LP and the voltage Vpg2_LP have a relationship ofVpg_LP>Vpg2_LP.

3.4 Effects of the Present Embodiment

With the configuration according to the present embodiment, the sameeffects as those of the first and second embodiments may be obtained.

Further, with the configuration according to the present embodiment, theHP/LP mode regulator 35 includes the PMOS transistor Mdrv2. Therefore,both the HP mode and the LP mode may be supported.

Further, with the configuration according to the present embodiment, thevoltage Vpg2_LP has the potential determined by the gate-source voltageVgs of the PMOS transistor Mdrv2. Therefore, the voltage Vpg2_LP may bedesigned to have the same potential as the voltage Vpg_HP. Thereby, thepotential difference between the voltage Vpg2_LP and the voltage Vpg_HPmay be made less than the potential difference between the voltageVpg_LP and the voltage Vpg_HP. Accordingly, the period untilstabilization may be shortened by charge sharing.

In addition, a configuration in which the PMOS transistor Msw6 isomitted from the HP mode regulator 33 described in FIG. 5 of the firstembodiment or FIG. 15 of the fifth example of the second embodiment maybe applied to the HP/LP mode regulator 35.

4. Fourth Embodiment

Next, a fourth embodiment will be described. In the fourth embodiment, aconfiguration of a memory system different from the first to thirdembodiments will be described. Differences from the first to thirdembodiments will be mainly described below.

4.1 Configuration of Memory System

First, an example of a configuration of the memory system will bedescribed with reference to FIG. 22. FIG. is a block diagramillustrating an example of a configuration of the memory system 1.

As illustrated in FIG. 22, the memory system 1 includes the plurality ofmemory chips 10, the memory controller 20, and a plurality of interfacechips (I/F chips) 40, and is connected to the external host device 2.

The memory chips 10 and the memory controller 20 are the same as thosein FIG. 1 of the first embodiment. The memory interface circuit 25 inthe memory controller 20 is connected to the plurality of memory chips10 via the interface chip 40.

The interface chip 40 may also have a part of the function of the memoryinterface circuit 25 built into the memory controller 20. By interposingthe interface chip 40 between the memory controller 20 and the memorychips 10, the load of the memory controller 20 caused when the memorycontroller 20 is connected to the plurality of memory chips 10 may bereduced. The interface chip 40 includes the power supply circuit 30,like the memory chip 10 and the memory controller 20. A voltage VCCQ_Iis externally applied to the power supply circuit 30 in the interfacechip 40. The voltage VCCQ_I may have the same voltage value as thevoltage VCCQ_C or the voltage VCCQ_M, or may have a different value.Further, the power supply circuit 30 in the interface chip 40 may havethe same configuration as the power supply circuit 30 in the memory chip10 or the memory controller 20, or may have a different configuration.

4.2 Effects of the Present Embodiment

With the configuration according to the present embodiment, the sameeffects as those of the first to third embodiments may be obtained.

5. Fifth Embodiment

Next, a fifth embodiment will be described. In the fifth embodiment, anexample of an information terminal system using the memory systemdescribed in the first to fourth embodiments will be described. Examplesof the information terminal system include without limitation mobilephones, cellular phones, smart phones, tablets, phablets, servers,computers, portable computers, desktop computers, personal digitalassistants (PDAs), monitors, computer monitors, televisions, tuners,radios, satellite radios, music players, digital music players, portablemusic players, digital video players, video players, digital video disc(DVD) players, portable digital video players, and automobiles.

5.1 Configuration of Information Terminal System

An example of a configuration of the information terminal system 1000will be described with reference to FIG. 23. FIG. 23 is a block diagramillustrating an example of a configuration of the information terminalsystem 1000.

As illustrated in FIG. 23, the information terminal system 1000 includesa CPU 1100, the memory system 1, a network interface device 1200, aninput device 1300, an output device 1400, a display controller 1500, anda display 1600.

The CPU 1100 controls the entire information terminal system 1000. TheCPU 1100 is connected to a system bus and communicates with otherdevices by exchanging address information, control information, and datainformation via the system bus. The CPU 1100 may include a processor andcache memory to provide quick access to temporarily stored data.

The network interface device 1200 is connected to the system bus. Thenetwork interface device 1200 may be any device configured to enable theexchange of data with a network. The network may be, for example, awired or wireless network, a private or public network, a local areanetwork (LAN), a wireless local area network (WLAN), a wide area network(WAN), or BLUETOOTH™. The network interface device 1200 may beconfigured to support any type of communication protocol if necessary.

The input device 1300 is connected to the system bus. The input device1300 may include a keyboard, a mouse, input keys, switches, a voiceprocessor for inputting data and others.

The output device 1400 is connected to the system bus. The output devicemay include a printer, a speaker, and audio, video, and other visualindicators for outputting data.

The display controller 1500 is connected to the system bus. The displaycontroller 1500 converts, for example, display information received fromthe CPU 1100 into a format suitable for the display 1600 and transmitsthe display information to the display 1600.

The display 1600 displays the display information received from thedisplay controller 1500. The display 1600 may be any type of displayincluding, for example, a cathode ray tube (CRT), a liquid crystaldisplay (LVD), or a plasma display.

5.2 Effects of the Present Embodiment

With the configuration according to the present embodiment, the sameeffects as those of the first to fourth embodiments may be obtained.

Moreover, with the configuration according to the present embodiment,the operation mode of the information terminal system may be switched ata high speed. Furthermore, the power consumption of the informationterminal system may be reduced.

6. Modifications and Others.

The semiconductor device according to the above embodiments includes theregulator 33 having first and second operation modes, and the regulatorincludes a first transistor Mdrv having one end connected to a powersupply voltage wiring (node N1) and a remaining end connected to anoutput terminal T2, a first resistance element RA having one endconnected to the first transistor and the output terminal, a secondresistance element RB having one end connected to a remaining end of thefirst resistance element and a remaining end connected to a groundvoltage wiring (node N2), a first circuit 310 connected to a gate of thefirst transistor to apply a first voltage Vpg depending on a differencebetween a reference voltage VREF_HP and an output voltage VOUT dividedby the first and second resistance elements to the gate of the firsttransistor, a first bias current IA in the first operation mode (LPmode) being less than a second bias current IA+IB in the secondoperation mode (HP mode), a first capacitor element C1 having one sideelectrode connected to the output terminal, and a second circuit 320connected to a remaining side electrode of the first capacitor elementand configured to electrically disconnect the first circuit from thefirst capacitor element and apply a second voltage Vc1_HP to the firstcapacitor element in the first operation mode and to electricallyconnect the first circuit to the first capacitor element in the secondoperation mode.

The above embodiments provide a semiconductor device capable ofimproving a processing capacity thereof.

In addition, the embodiments are not limited to the above-describedforms, and various modifications thereof are possible. For example, thefirst to fifth embodiments may be combined as much as possible. Forexample, the VOUT load current circuit 330 described in FIG. 10 of thesecond example of the second embodiment may be applied to FIG. 12 of thethird example of the second embodiment, and the boost circuit 350described in FIG. 15 of the fifth example of the second embodiment maybe applied thereto.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A semiconductor device having a regulator havingfirst and second operation modes, the regulator comprising: a firsttransistor including a first end configured to be connected to a powersupply voltage and a second end connected to an output terminal; a firstresistor having a first end connected to the first transistor and theoutput terminal; a second resistor having a first end connected to asecond end of the first resistor and a second end connected to a groundvoltage; a first circuit configured to apply a first voltage to a gateof the first transistor, wherein the first voltage is determined basedon a difference between a reference voltage and an output voltagedivided by the first and second resistors, and wherein a first biascurrent flowing through the first circuit in the first operation mode isless than a second bias current flowing through the first circuit in thesecond operation mode; a capacitor including a first electrode connectedto the output terminal; and a second circuit connected to a secondelectrode of the capacitor and configured to: (a) electricallydisconnect the first circuit from the first capacitor and apply a secondvoltage to the first capacitor in the first operation mode, and (b)electrically connect the first circuit to the capacitor in the secondoperation mode.
 2. The semiconductor device according to claim 1,wherein the second voltage is determined based on a third voltageapplied to the capacitor in the second operation mode.
 3. Thesemiconductor device according to claim 1, wherein the first circuitincludes a second transistor having a source configured to be connectedto the ground voltage, and a drain of the second transistor is connectedto the second electrode of the capacitor via the second circuit in thesecond operation mode, and wherein the second voltage is equal to orhigher than a drain voltage under which the second transistor operates.4. The semiconductor device according to claim 1, wherein the secondcircuit electrically connects the power supply voltage to the gate ofthe first transistor in the first operation mode.
 5. The semiconductordevice according to claim 1, wherein the regulator further includes afifth circuit configured to flow a third bias current greater than thesecond bias current flowing through the first circuit during a switchingperiod from the first operation mode to the second operation mode.
 6. Asemiconductor device including a regulator having first and secondoperation modes, the regulator comprising: a first transistor includinga first end connected to a power supply voltage; a first resistorincluding a first end connected to an output terminal; a second resistorincluding a first end connected to a second end of the first resistorand a second end connected to a ground voltage; a first circuitconfigured to output a first voltage that is determined based on adifference between a reference voltage and an output voltage divided bythe first and second resistors, wherein a first bias current flowingthrough the first circuit in the first operation mode is less than asecond bias current flowing through the first circuit in the secondoperation mode; a first capacitor having a first electrode connected tothe first circuit and a second electrode connected to the outputterminal; and a second circuit configured to: electrically disconnectthe first circuit from a gate of the first transistor; electricallydisconnect a second end of the first transistor from the outputterminal; apply a second voltage to the gate of the first transistor inthe first operation mode; and electrically connect the first circuit tothe gate of the first transistor and electrically connect the second endof the first transistor to the output terminal in the second operationmode.
 7. The semiconductor device according to claim 6, wherein thesecond voltage is equal to the first voltage applied to the gate of thefirst transistor in the second operation mode.
 8. The semiconductordevice according to claim 6, wherein the regulator includes a thirdresistor having a first end connected to the output terminal, andfurther includes a third circuit configured to electrically disconnect asecond end of the third resistor from the ground voltage in the firstoperation mode and to electrically connect the second end of the thirdresistor to the ground voltage in the second operation mode.
 9. Thesemiconductor device according to claim 6, wherein the regulator furtherincludes a fourth circuit including a second capacitor having a firstelectrode connected to the power supply voltage and a fourth resistorhaving a first end connected to a second electrode of the secondcapacitor and a second end connected to the gate of the firsttransistor.
 10. The semiconductor device according to claim 6, whereinthe regulator further includes: a fifth circuit including a thirdtransistor having a first end connected to the output terminal andconfigured to electrically disconnect a second end of the thirdtransistor from the ground voltage in the first operation mode and toelectrically connect the second end of the third transistor to theground voltage in the second operation mode; and a sixth circuitconfigured to apply a third voltage to a gate of the third transistorduring a switching period from the first operation mode to the secondoperation mode and to apply a fourth voltage lower than the thirdvoltage to the gate of the third transistor after the switching period.11. A semiconductor device comprising a regulator having first andsecond operation modes, wherein the regulator includes: a firsttransistor including a first end configured to be connected to a powersupply voltage; a first resistor having a first end connected to anoutput terminal; a second resistor having a first end connected to asecond end of the first resistor and a second end connected to a groundvoltage; a first circuit configured to apply a first voltage to the gateof the first transistor, wherein the first voltage is determined basedon a difference between a reference voltage and an output voltagedivided by the first and second resistors, wherein a first bias currentflowing through the first circuit in the first operation mode is lessthan a second bias current flowing through the first circuit in thesecond operation mode; a first capacitor having a first electrodeconnected to the first circuit and a second electrode connected to theoutput terminal; a second circuit including a second capacitor having afirst electrode connected to the power supply voltage and a fourthresistor having a first end connected to a second electrode of thesecond capacitor; and a third circuit configured to: electricallydisconnect the second circuit from the gate of the first transistor andelectrically disconnect a second end of the first transistor from theoutput terminal in the first operation mode; and electrically connectthe second circuit to the gate of the first transistor and electricallyconnect the second end of the first transistor to the output terminal inthe second operation mode.
 12. The semiconductor device according toclaim 11, wherein the third circuit is further configured toelectrically connect the power supply voltage to the gate of the firsttransistor in the first operation mode.
 13. A semiconductor devicecomprising a regulator having first and second operating modes, whereinthe regulator includes: a first transistor including a first endconnected to a power supply voltage; a fourth transistor including afirst end connected to the power supply voltage and a second endconnected to an output terminal; a first resistor having a first endconnected to the output terminal; a second resistor having a first endconnected to a second end of the first resistor and a second endconnected to a ground voltage; a first circuit configured to apply afirst voltage to a gate of the fourth transistor, wherein the firstvoltage is determined based on a difference between a reference voltageand an output voltage divided by the first and second resistors, andwherein a first bias current flowing through the first circuit in thefirst operation mode is less than a second bias current flowing throughthe first circuit in the second operation mode; a capacitor having afirst electrode connected to the first circuit and a second electrodeconnected to the output terminal; and a second circuit configured to:electrically disconnect the first circuit from a gate of the firsttransistor; electrically disconnect a second end of the first transistorfrom the output terminal; apply a second voltage to the gate of thefirst transistor in the first operation mode; and electrically connectthe first circuit to the gate of the first transistor and electricallyconnect the second end of the first transistor to the output terminal inthe second operation mode.
 14. A memory system comprising: a pluralityof memory chips, each of which includes a regulator having first andsecond operation modes; and a memory controller that includes theregulator and is connected to the plurality of memory chips, wherein theregulator includes: a first transistor including a first end connectedto a power supply voltage; a first resistor having a first end connectedto an output terminal; a second resistor having a first end connected toa second end of the first resistor and a second end connected to aground voltage; a first circuit configured to output a first voltage,wherein the first voltage is determined based on a difference between areference voltage and an output voltage divided by the first and secondresistors, and wherein a first bias current flowing through the firstcircuit in the first operation mode is less than a second bias currentflowing through the first circuit in the second operation mode; acapacitor having a first electrode connected to the first circuit and asecond electrode connected to the output terminal; and a second circuitconfigured to: electrically disconnect the first circuit from a gate ofthe first transistor; electrically disconnect a second end of the firsttransistor from the output terminal; apply a second voltage to the gateof the first transistor in the first operation mode; and electricallyconnect the first circuit to the gate of the first transistor andelectrically connect the second end of the first transistor to theoutput terminal in the second operation mode.
 15. The memory systemaccording to claim 14, wherein, when selecting one of the plurality ofmemory chips, the memory controller switches an operation mode of theselected memory chip from the first operation mode to the secondoperation mode.